Corner weights

 I have been concerned about the corner weights since a) running into the Kombi and b) Breaking a NS upper wishbone (on a speed bump I suspect). I have just done the Westfield Megabusa track car so it is now time for the J15.  There is a very good on line spread sheet and explanation of how to set up your car at: https://robrobinette.com/corner_weight_calc.htm

There is also a very good Excel spread sheet by Nick Warinner of ntw@360racing.com that I copied and modified to add the cross weight calculation information recommended in the above advisory site.

Cross weight = (Right Front + Left Rear)/Total weight.

I also purchased a set of Proform Bluetooth corner weight measuring pads from ebay tegiwaimports these are a budget product but works well and is easy to use.

Here are the results, you will have to open the image by double clicking it.
In summary I did the following.
1) Ensure the tyres are all the same pressure
2) The suspension height front and back are correct. In my case the lower front wishbones are horizontal and the front to back was 20mm
3) Adjust all the spring lengths FL = FR and RL = RR as a good starting point.

Before adjustment

After adjustment no driver

With driver

In summary I can see no issues with the suspension, the initial setup was done with a ruler and gives acceptable results only 1% out. The key issue is confidence the car is right.

Like the Busa I cannot see the advantage in my car of biasing it to handle with the driver only as it only makes a 0.3% difference. It means the handling is optimal with a passenger also depending on weight.

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Damaged rear tub

Bad day yesterday (16th April 2015), should have stayed in bed, the handbrake failed to grip on the hill and the J15 ploughed into my (new to me) VW Kombi. The damage to both vehicles was fairly extensive. The tailgate (large rear single door) on the Kombi needs the expertise of a body shop work. The damage to the bumper fixings and steps I managed to sort out myself. The J15 had at least 4 holes in the rear tub, bent  the hinge assembly and the fog light was ripped off. I have shown the GRP layer after removing the worst of the damage with a grinder so you can see the real extent of it.

GRP layers delaminated



More delamination near Fog light



damage extended from large hole



GRP repaired fairly quickly and the Gel coat applied by brush

First  gel  coat sanded down, GRP showing thru in a couple of places Not bad so far!



GRP showing thru on curved edge

Wax additive

I went to get some more gel coat from my friendly supplier in Rutherglen, he tells me there is a wax that you can add to the gel coat during the mixing process. I found this article on the matter: http://www.easycomposites.co.uk/products/polyester-resin/solution-mw-wax-gelcoat-additive.aspx

And it works......

 

The wax allows far better setting times without the use of packing tape or cling film to exclude the air.


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Air filter protection from road dust

The Sylva J15 was designed to take the 1.7L Sigma engine. In my interpretation of the engine install The air filter and MAF sensor ended up perilously close to the rear wheel. In inclement weather (in Scotland) it gets covered in water off the rear wheel. The problems are two fold 1) Air filter contamination 2) MAF meter reliability. The ECU in my  car is stock with a Puma Speed upgrade. As such it is a closed loop system with air flow as part of the Ford mapping. I decided to fence off the route for contamination from the back wheel. This is the penultimate winter mod as it is now on the cusp of Spring in Scotland.

Contents
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More running lights

The problem with driving the Sylva J15 on roads is some other drivers just don't see you. I was driving my car last spring (2014) on a straight but slightly undulating road at 60mph. To my horror the car coming towards me was occupying the same lane as me, he was overtaking a pair of cyclists and just did not see me. The car has track tyres and the road was dry so I was able to avoid a head on collision, just.

I decided to fit a set of LED running lights higher up so I can be seen from a greater distance. I turned a steel bar, drilled, taped and welded it to the Roll-over-bar and painted to match.

Mounting on roll bar

Contents
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Yet another steering wheel

I have tried several steering wheels on the J15 and none so far, has satisfied my desire for handling. The rake of the J15 aero screen means only a small diameter wheel will fit my car.

I spotted a 260mm Racetech for sale on Locostbuilders (yellowcab) that has a nice sued leather covering making it very comfortable to handle. The last one I tried of that size had a D shaped and I did not like that at all.

Of course the Racetech  would not fit the 70mm PCD 6 x 70mm existing mounting so a plan was hatched. I took a 2" x 82mm long billet of aluminium bar and cut it on the lathe and CNC mill.

I bored the centre thru at 30mm followed by a hollowing out of the centre to 50mm, this lightened the adapter. Then placed in CNC mill to pop the holes at the 60deg and 120 deg PCD's. The steering wheel has a 50mm PCD and the boss a 70mm PCD. The screws attaching it to the boss are down a 45mm countersink hole. I do believe you can fit any steering wheel to any car with a lump of aluminium and a plan.



Here is the result:

Billet with centre hole and Racetech mounting note c/s holes

Wheel mounted on billet

70mm PCD x 6 fixings

On the car

Only time will tell if this is the last incarnation.

Contents
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Year two summary

I have had a wonderful summer going to every available track day with either the Westfield or the Sylva but mostly with the Westfield. The Westfield is more of raw track car. However the Sylva has had problems left over from the initial build that can only be fully explored on a track. It is the engineering of the car into a better state that keeps my interest going forward. The Sylva was reliable enough early in the year to go to Stoneleigh and Applecross total distances of 1500 - 2000 miles.

After the above trips the problems summarised were:

* Inadequate protection from the roll-over-bar.
* Throttle response giving unpredictable engine braking.
* Engine mounts that wanted to destroy themselves.
* Brake effectiveness was poor.
* Complaints from track marshals about fuel spillage from my tank overflow pipe.
*  Handling was poor going into and out of the hairpins (it scared me!).

If you follow the previous blog entries you will see that I have addressed all of these issues. Although I have spend most of my efforts this year on the Westfield I have spent a considerable amount of time recently on the Sylva. I was able to confidently drive around Kames lately and I think these videos summarises the progress better than words.

http://youtu.be/_uidzWq31YQ

http://youtu.be/FhXoJRMqCfQ

Contents
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Anti-roll bars ARB

I have been trying to improve my track times in the Sylva J15. My impression is there is some over steer going into a corner that is not to my liking. One of the ways of controlling this is to fit front and rear ARB's and play about with them on a track. I have times on a dry day recorded on my RaceChrono app in my smart phone. All I need now is to try out these ARB's and plot the difference.

Rear

Unfortunately Sylva Autokits don't do an ARB for the J15, however Playskool do one for the Westfield that is a very useful starting point for the design. I copied the design of  the two alloy pivots from the Playskool parts on my Westfield modified of course to suit the Sylva. The drop links are standard 100mm x M8 parts from McGill Motorsport. The chassis attachment point braketry was a custom fabrication. It is bolted to the rear chassis rail and the (old) Roll bar attachment points near the top of the coil springs. I wanted something that was simple to adjust when finished as I don't know how much compensation to set the bars up for. The roll bar is fabricated out of seamless spring steel 3mm wall thickness 19,mm tube obtained from Blakes Metal Store and bent using a hydraulic former with a 1040mm curved right angle at both ends..

Adjustment points

Drop link ball joint to wishbone

Offside arrangement

Nearside arangement

ARB Bearing arrangement



Detail of drop link

Rear fully assembled

Front

The front design is technically simpler than the rear (no custom extended mounts) but there is a lot of stuff to come off the car  including draining the radiator and removing the front clamshell. In my case the brackets mounting the radiator had to be remodelled to allow the ARB bar to pass between the upper chassis rail and the cooling fan. Also the alloy plate around the pivot point site had to be relieved using a dremmel and a chassis weld flattened. I used captive threaded studs welded from the rear to secure the pivot points, however bolts and spacers passing thu the chassis would have worked assuming they are long enough. The ARB bar shape has to take into account the relatively large steering angle change from lock to lock. The initial bend of the ARB was contacting the wheel on full lock so adjustment to the initial simple design was made. The bar is made of spring steel and ideally needs a hydraulic bender to implement.

General layout



Trial fitting the front

Radiator back in

Adjustment
I plan to base the initial settings based on an article and spreadsheet by "Keen tnkerer" on the WSCC site. I will be in contact with him shortly.

Contents
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